Core networks are evolving to packet switched networks and old TDM-type networks are gradually being replaced. However many legacy TDM services still exist. These TDM services may be for trunking links (T1/E1/DS3/SONET/SDH) or for voice services, for example. Circuit Emulation Services (CES) are used to provide TDM services in IP/MPLS networks in order to take advantage of these packet switched networks. A TDM Pseudowire (PW) is established across the packet switched network. TDM frames are received from an access circuit at a router at the edge of the packet switched network through an access port on the router. The router then encapsulates the TDM frames and transmits the encapsulated TDM data as packets to a receiving router over the TDM-PW through the packet switched network. IETF and MEF have multiple standards that define how to encapsulate TDM services into TDM-PWs.
If the router receives an indication from the access circuit that the access circuit is not in a normal state (e.g. LOS, LOF, AIS), the router signals the receiving router of this by setting the L bit in the LRM bits of the TDM-PW control word to a value of “1”. The receiving router knows to ignore any packets in which the L bit has been set to “1”. However the transmitting router still sends packets to the receiving router, even though there is no valid TDM data to send. In one implementation, the transmitting router still sends packets to the receiving router with the invalid TDM data as payload. In another implementation, if the option to suppress the TDM data is chosen, the transmitting router does not send payload data. However even if the payload is being suppressed, the transmitting router still sends packets, containing only encapsulation headers, to the receiving router. Since the header in a TDM CES packet can make up as much as 95% of the size of the whole packet, this results in little saving of bandwidth.
Even though the bandwidth of TDM PWs in routers is usually small compared to the bandwidth used by other IP or Ethernet services, there are many instances where network operators have small network links and the TDM PW bandwidth is too high. Examples of small network links are microwave communication links and N×T1 channels in SONET. There is a need to provide a method and system in which the network operator has more flexibility regarding bandwidth usage in CES.